ios - 是否有将 UIColor 转换为 Hue Saturation Brightness 的功能？

Question

我可以用 RGB 值设置 uicolor:

[UIColor colorWithRed:0.53 green:0.37 blue:0.11 alpha:1.00];

我可以用 hsb 值设置 uicolor:

[UIColor colorWithHue:0.10 saturation:0.16 brightness:0.13 alpha:1.00];

我也可以将它转换回 RGB:

CGFloat* colors = CGColorGetComponents(Color1.CGColor);

但是我怎样才能从 uicolor 获得 HSB 呢？

Answer 1

使用 UIColor 方法:getHue:饱和度:亮度:alpha:

来自 Apple 文档:
“返回构成 HSB 颜色空间中颜色的分量。”

- (BOOL)getHue:(CGFloat *)hue saturation:(CGFloat *)saturation brightness:(CGFloat *)brightness alpha:(CGFloat *)alpha

例子:

UIColor *testColor = [UIColor colorWithRed:0.53 green:0.37 blue:0.11 alpha:1.00];

CGFloat hue;
CGFloat saturation;
CGFloat brightness;
CGFloat alpha;
BOOL success = [testColor getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha];
NSLog(@"success: %i hue: %0.2f, saturation: %0.2f, brightness: %0.2f, alpha: %0.2f", success, hue, saturation, brightness, alpha);

NSLog 输出:

success: 1 hue: 0.10, saturation: 0.79, brightness: 0.53, alpha: 1.00

这是@WhiteTiger 提供的方法的更正版本:

// Test values
CGFloat red = 0.53;
CGFloat green = 0.37;
CGFloat blue = 0.11;

CGFloat hue = 0;
CGFloat saturation = 0;
CGFloat brightness = 0;

CGFloat minRGB = MIN(red, MIN(green,blue));
CGFloat maxRGB = MAX(red, MAX(green,blue));

if (minRGB==maxRGB) {
    hue = 0;
    saturation = 0;
    brightness = minRGB;
} else {
    CGFloat d = (red==minRGB) ? green-blue : ((blue==minRGB) ? red-green : blue-red);
    CGFloat h = (red==minRGB) ? 3 : ((blue==minRGB) ? 1 : 5);
    hue = (h - d/(maxRGB - minRGB)) / 6.0;
    saturation = (maxRGB - minRGB)/maxRGB;
    brightness = maxRGB;
}
NSLog(@"hue: %0.2f, saturation: %0.2f, value: %0.2f", hue, saturation, brightness);

NSLog 输出:

hue: 0.10, saturation: 0.79, value: 0.53